CHEM 2443 Exam 2

How is regioselectivity determined?

C+ rank determines regioselectivity. The higher the difference in rank between possible places for C+ to form, the higher the regioselectivity

Functional group: OH

alcohol

Functional group: NH2

Amine

Functional group: R-O-R

Ether

Functional group: SH

thiol

Functional group: O=C-H-R

aldehyde

Functional group: O=R

ketone

How do you determine Meso compounds?

Symmetrical, with asymmetric centers

How do you determine chiral compounds?

No plane of symmetry, but with asymmetric centers

Specific rotation equation

[α]θλ = α/l*c

where alpha = observed rotation, l = length of tube in decimeters, c = sample concentration in g/mL

Enantiomers

isomers that are mirror images but not superimposable

diasteremoers

isomers that are not mirror images or superimposable

Hydrohalogenation (H-Br)

Markovnikov normal

Acid-catalyzed Hydration (H2O + H2SO4)

OH + H markovnikov H is 1st

If you have a weird molecule like CH3OH instead of your usual, what do you do?

Do it normally, but make sure that you keep the added on groups attached.

Halogenation (Br-Br + CH2Cl2)

Anti-addition

Halohydrin Formation (Br2 + H2O)

Br + OH Anti-addition Br 1st

Hydrogen addition (H2)

Syn

Hydroboration Oxidation (BH3 + other stuff)

H + OH, Syn antimarkovnikov, no C+, OH 1st

Oxymercuration (Hg(OAc)2 + other stuff)

OH + H, Markovnikov, no C+, no shift

Ozonolysis (O3)

Splits double bond completely, and forms two groups you already know

Molecules can't be diastereomers if:

They have less than 2 assymetric centers, no double bond, or no ring